Sparkproof flooring



Mgbsfeys June 1.9, 1945. w. w. DQNELSON ETAL SPARKPROOF FLOORING Filedseppqz?, 1941 y ii Patented June 19, 1945 UNITED STATES PATENT oFFIcE SPARKPROOF FLOORING William W. Donelson, Boston, and John W. Downey, Newton Center, Mass., assigner-sto The Federal Flooring Corporatin, Boston, Mass., a corporation of Massachusetts Application September 27, 1941, Serial No. 412,668

Claims.

This invention relates to sparkproof flooring and more particularly concerns a novel and economical flooring especially adapted to conduct to the ground static electrical charges from articles coming in Contact with the flooring, thereby eliminating these charges and the dangers they present. We are aware that these dangers have been known heretofore and that certain flooring constructions have been suggested for eliminating the same. Such flooring has, however, been objectionable for various reasons among which are chiefly mentioned the objectionable character of the flooring, the excessive cost of construction, and failure to dissipate static charges at a safe minimum resistance. The primary object of our invention is the production yoi an improved sparkproof flooring in which the desirable characteristics are not diminished because of the sparkproof features incorporated therein, which flooring can be constructed at a cost little in excess of ordinary flooring and will dissipate static charges from any point thereon at a safe minimum resistance.

One embodiment of our invention contemplates a sparkproof flooring comprising a sub-floor and a top floor thereon of conductive plastic composition and having grounded conductive wires incorporated therein at such `limited predetermined distances apart and beneath the top surface of the flooring as to receive and discharge static electric charges from articles coming in contact with any portion of the top surface. In the interest of economy and simplicity of construction, these wires preferably comprise a single wire strand looped back and forthin taut condition across the flooring in a plurality of reaches, the loops being supported by hooks or the like previously anchored in the walls or flooring at the proper elevations and locations. The Iwires are placed at the predetermined spacing and level above the sub-floor and in position to receive the top flooring thereonto.

A preferredmethod of procedure contemplates first the laying of a portion of the top floor on the sub-floor to an elevation corresponding substantially to the proposed location of the conductive Wires, the placing of the wires in position thereabove and at the predetermined distance beneath the predetermined vtop surface of the finished flooring, and thereafter completing lthe top floor by a layer of conductive plastic composition covering the wires and reaching an elevation corresponding to the predetermined top surface of the finished floor.

A further embodiment of the invention GQ11- templates the flooring substantially as above de scribed ybut having in addition thereto conductive studs driven into the sub-floor in contact with the conductive wires and serving directly to dissipate static charges from articles coming in contact with the studs at the flooring surface, the top surfaces of the studs being exposed and substantially flush with the top surface of the ooring `and in a predetermined and relatively close relationship.

The production of improved and economical flooring of the above described nature together with the novel and relatively simple method of constructingthe same comprises a further object of the invention. These and other features of the invention will be best understood and appreciated from the following description of preferred embodiments thereof selected for purposes of i1- lustration and shown in the accompanying drawing wherein:

Fig. 1 is a fragmentary view of a flooring constructed in accordance with one embodiment of our invention, portions thereof being broken away to illustrate the process of construction,

Fig, 2 is a like View of a modified construction,

Fig. 'Bis a like view of a further modified construction,

Fig. 4 is an enlarged view of a stud employed in the flooring ofFig. 3.

Referring first to Fig. 1 of the drawing, I0 indicateg a sub-floor of wood, concrete or other material and I2 indicates the top flooring thereover. In proceeding with the construction of a flooring of this nature, we first form the sub-floor I0 together with side walls I4. The side Walls are then covered with a layer `I 6 of the same material used to form the top floor l2. This material is in the nature of a plastic composition which can be spread out to the desired thickness. The material which we preferably employ is a plastic cementitious composition embodying magnesite, the magneste being adapted to form a top flooring having desirable characteristics and being sufficiently .conductive to carry out the static spark eliminating function of the invention. It will 'be understood however that the top flooring is not to be considered yas limited to any particular material other than a plastic composition embodying one or more ingredients rendering the composition sufficiently-conductive of electricity. The magnesite composition which we use is also non-productive of heatsparks due to the contact of tools or the like therewith and it is highly desirable that any composition employed in the y top flooring shall be of this nature.

The finished surface at `I6 is preferably of the shape illustrated in Fig. 1 whereby to eliminate dirt catching corners and facilitate cleaning of the room, and the edge at I8 is of a thickness corresponding to the predetermined thickness of the top flooring. Our invention contemplates the incorporation of conductive wires in the top flooring and located at a predetermined distance apart and from the top surface of the flooring. In accordance with our invention, we locate these wires definitely in predetermined position before laying the top fiooring thereonto and the accuracy of this location throughout the entire length of the wires is assured by placing the wires under substantial tension holding them at a predetermined distance beneath the predetermined top surface of the flooring to be formed. In the interest of economy of both labor and material, we preferably employ a single wire strand looped into a plurality of reaches as illustrated in Fig. 1.

When laying the side walls I6 and before the material thereof has set, we place aplurality of hook-like elements 22 in anchoring position thereon and projecting outwardly of the edge thereof over the sub-floor I0. The element 22 has a hook at one end and a laterally extending key portion 23 at its other end. The key end is inserted into the soft material and turned to a position giving the key a firm hold on the material. These elements are located a predetermined distance apart and at a predetermined elevaton. We then proceed with the laying of the t'op floor by laying a portion 24 thereof of a thickness reaching substantially to the hooks 22 and the position at which the conductive Wires are to be located. The wire 20 is then looped over the hooks 22 and stretched to taut condition holding the reaches thereof substantially straight horizontally and vertically and located at the predetermined distance from the predetermined top surface of the finished flooring. The top floor is then completed by placing the top layer 26 over the bottom layer 24 and enclosing the Wires, the wires being grounded at 28. We have found that a layer 24 of one-quarter inch to one-half inch thickness and a layer 26 of three-sixteenths to one-quarter inch thickness produces very satisfactory results.

While the procedure above described is believed to be preferable, our invention is not to be considered as limited thereto since numerous modifications in both operation and structure will be quite apparent. For example, the wires can be placed in position above the sub-floor before placing any of the top floor, and the top flooring can then be laid in a single operation. The twolayer method first above described is however more convenient and preferred.

In case a wall portion IB is not employed, the wire supporting hooks can be anchored within the flooring 24 beneath the top layer 26. As illustrated in Fig. 2, anchoring elements 30 are inserted into the sub-floor layer 34, before the cement has set, and the hook portions thereof are extended upwardly to the desired Wire supporting position, prior to the placing of the wires 36 and the top layer 38. It will lbe apparent that while the layers 24 and 34, beneath the top layers, are described as a part of the top flooring they can be and are also considered, for purposes of our invention, a part of the sub-floor adapted to receive the finishing top floor.

Definite safety standards for sparkproof ooring were established by the National Fire Protection Association at its th annual meeting in Toronto, Canada, May 12-16, 1941. These standards demand that the resistance to the passage of an electric current from any point on the surface of the ooring to the ground shall not exceed 10,000 ohms, such electrically conductive path between any body making electric contact with the flooring being essential if the building up of dangerous static charges is to be eliminated. Our improved flooring has been constructed with this requirement definitely in mind and the wires in our flooring are so spaced from each other and from the top surface of the flooring, together with the conductivity of the top floor, that the resistance to the ground from any point on the top surface of our flooring does not exceed 10,000 ohms. It will also be understood that uniformity of these spacings and the straight continuity of the wire, resulting from its taut condition during the construction of the flooring, are essential for maximum efficiency and such uniformity is definitely assured by proceeding in accordance with our invention. The spacing which we have so far employed to secure this result comprises the placing of the wires 2 apart and a distance of approximately fr from the top surface of the flooring.

While the flooring construction above described is extremely economical in labor and materials, it may be desirable in some cases to provide the flooring with direct conductive contacts at the flooring surface. A further feature of our invention embodying such construction is illustrated in Figs. 3 and 4 of the drawing. The sub-floor 40 and the sub-floor portion 42 thereon together with the wires 44 are the same as the corresponding construction illustrated in Fig. 1, the wire being held taut over the hooks at the ends of the reaches. In this case however, before laying the top portion 46, we drive studs 4B into the flooring in relatively close relationship and in electro-conductive engagement with the wires.

This operation is facilitated by the use of a templet 50 of a thickness corresponding to the thickness of the predetermined top floor 46 and having holes 52 therethrough of a size permitting the passage of the stud heads. The holes are spaced each way a distance corresponding to the spacing of the wires 44 and the stud heads are of a thickness to firmly engage the wires when the studs are driven into the locations permitted by the templet. When the templet is removed the studs will be positioned uniformly and at uniform levels as will be understood. We then proceed to apply the top layer 46 which may thereafter be ground or polished to a degree exposing the stud heads. The studs are located sufficiently close to cause at least one stud to be engaged by any element coming in contact with the floor and at least the head portions of the studs are preferably of non-ferrous metal whereby to eliminate the possibility of sparking should a tool or any element fall into contact therewith. Thus the flooring is sparkproof from either static charges or heat sparks generated from impact. While the top layer of this flooring need not necessarily be conductive of electricity we prefer that it shall be of the same material comprising the layer 26.

It will now be apparent that we have produced a superior flooring for the purpose described and have produced the same ina most economical and convenient manner. The conductive wire used is relatively inexpensive and the method employed in its incorporation into the flooring assures `the locating of the wire exactly and uniformly at the'desired depth throughout the entire iiooring area, this being of considerable im portance for the purpose of quickly and uniformly dissipating any static charges coming in contact with the top surface of the iiooring. The invention is also adapted to produce either the direct contact iiooring illustrated in Fig. 3 or the plain flooring illustrated in Figs. l' and 2 and employing conductive composition enclosing the conductive wires, the magnesite composition also eliminating the danger of sparks produced by frictional contact of any element with the floor.

Having thus described our invention what We claim as new and desire to secure by Letters Patent of the United States is:

1. A method of constructing sparkproof flooring over a sub-floor, which consists in stretching and holding to taut condition conductive Wire over the sub-floor in position located a predetermined distance beneath the predetermined top surface of the flooring to be formed, grounding said Wire, and forming over the sub-iioor a top iioor of conductive plastic composition enclosing the wire to a depth equal to said predetermined distance, whereby providing a uniformly conductive sparkproof flooring.

2. A method of constructing sparkproof flooring over a sub-Hoor, Which consists in stretching and holding to taut condition a conductive wire looped over the sub-floor in a plurality of reaches and located a predetermined distance beneath the predetermined top surfaceof the flooring to be formed, grounding said wire, and forming on the sub-hoor a top floor of conductive plastic composition enclosing the wire to a depth equal to said predetermined distance, whereby providing a sparkproof iiooring having conductive Wire therein uniformly located throughout its length.

3. A method of constructing sparkproof flooring over a sub-floor, which consists in stretching to taut condition conductive wires over the subfloor and located a predetermined distance beneath the predetermined top surface of the flooring to be formed, grounding said wires, driving conductive studs into the sub-hoor in contact with the Wires, the driven studs extending to a substantially uniform and predetermined elevation and being located in a predetermined and` relatively close relationship, and forming over the sub-Hoor a top fioor of plastic composition enclosing the wires and studs but leaving the top surfaces of the studs located substantially at the ooring surface.

4. A method of constructing sparkproof iiooring over a sub-floor, which consists in forming on the sub-floor a predetermined thickness of top flooring from plastic composition, supporting conductive Wires in taut condition thereover and adjacent thereto and located a predetermined distance beneath the top surface of the flooring to be formed, grounding said Wires, driving conductive studs into the top flooring in contact with the wires, the driven studs extending to a, substantially uniform and predetermined elevation and being located in a predetermined and relatively close relationship, and thereafter completing the top-flooring by applying over the firstnamed thickness thereof further plastic composition enclosing the Wires and studs but leaving the top surfaces of the studs located substantially at the flooring surface.

5. A method of constructing sparkproof nooring over a sub-oor, which consists in supporting conductive Wires thereover and located at a predetermined distance beneath the predetermined top surface of the flooring to be formed, grounding said wires, driving conductive studs into the sub-floor in contact with the Wires, the driven studs extending to a substantially uniform and predetermined elevation and being located in a predetermined and relatively close relationship, and forming over the sub-floor a top floor of plastic composition enclosing the wires and studs but leaving the top surfaces of the studs located substantially at the ooring surface.

6. A method of constructing sparkproof flooring over a sub-floor, which consists in supporting conductive Wires thereover and adjacent thereto, grounding said wires, driving conductive studs into the sub-floor in contact with the wires, the driven studs extending to a substantially uniform and predetermined elevation and being located in a predetermined and relatively close relationship, forming over the sub-floor a top floor of plastic composition enclosing the wires and studs, and grinding the top surface of the flooring to a level exposing the top surfaces of the studs. y

'7. Sparkproof flooring comprising a sub-door, grounded conductive wires thereon, conductive studs driven into the sub-iioor and into contact with the wires, and a top fiooring of plastic ccmposition enclosing the wires and studs, the studs being in a predetermined and relatively close relationship and their top surfaces being exposed and substantially flush with the top surface of the flooring. I

8. Sparkproof ooring comprising a sub-floor, a predetermined thickness of plastic composition top flooring thereon, grounded conductive wires on the top flooring, conductive studs driven into the top flooring and into contact with the wires, and further plastic composition on the firstnamed top flooring enclosing the wires and studs and completing the top flooring, the studs being in a predetermined and relatively close relationship and their top surfaces being exposed and substantially flush with the top surface of the flooring.

9. Sparkproof flooring comprising grounded conductive wires substantially parallel with and located a predetermined distance below the top surface of the iiooring, land conductive studs driven into the flooring and into contact with the wires, the top end portions of the studs being of non-ferrous metal and the top surfaces thereof being exposed and substantially flush with the top surface of the flooring and in a predetermined and relatively close relationship.

l0. Sparkproof flooring comprising a sub-iioor, a grounded conductor thereon, a top flooring on the conductor and sub-floor, and electro-conductive studs extending downwardly through the top iiooring and into contact with the conductor, the studs being in a predetermined and relatively close relationshipl and their top surfaces being exposed and substantially flush with the top surface of the iioorlng.

WILLIAM W. DONELSON. JOHN W. DOWNEY. 

